OP SOUTIIEEN INDIA. 17i> 



attenuatis ; declivitate antica infra mnbones parvulis adpressls paululum excavata, 

 delude uniforme in convexitate marginis anterioris transeunte ; declicitate posticu 

 fere recta, leclsshne curvata et cum terminatione piostica angulum obiusum 

 formante ', lumda haud distincta ; area longa, profunda;fidcris crassis et ligamento 

 prominente ; sinu pallii angiisto, rapide ascendente, apice obtuse acidiuscido ; super- 

 ficie striis suhtilibus numerosissimis ac nonnuilis snlcls magis profimdis sed noii 

 precipue latis tecta. 



Length of largest specimen ... ... ... ... 54 m. m. 



Height : length ... ... ... ... O'SO 



Thickncs.s : height ... ... ... ... O'-IS 



Shell elongately and broadly ovate, ratlier compressed, tliickest about tlie 

 middle, aud sloping regularly towards the attenuated and sharp margins (except 

 near the area), and also towards the beaks which are somewhat depressed and very 

 close together. There is no special lunula, bu.t the lunular region is slightly concave 

 below the beaks, passing immediately into the curve of the somewhat produced 

 anterior end ; the ventral margin is also slightly curved and the area still less so, 

 the latter forming thick obtuse edges along the extended area ; the posterior end is 

 broadly and somewhat roundly truncated. The surface of the shell is covered with 

 concentric striae, among which some are stronger than others, but the intermixed 

 sulci are not particularly broad. The pallial sinus when compared with that of the 

 next species is narrower, slightly longer, aud more rapidly ascending. 



Localities. — East aud south-east of Anapaudy, north of Alundanapooram, 

 aud south-east of Arrialoor, in a brownish, or (at the last loc.) iu a whitish sand- 

 stone ; rare. 



Formations. — Trichinopoly and Arrialoor groups (only one specimen from the 

 latter) . 



2. Ctprimeria Oldhamiana, Stoliczka, PI. V, Pigs. 21-25, aud PI. VI, Pigs. 1-5. 

 Cgj^- testa fere orbicidata, undiqite ad margines rotundata, declivitate lunulare 

 infra umbones paididum concaviuscula, declivitate areale moderate curvata ; umbo- 

 nibits parois, acutis et approximatis ; lumda haud marginata ; area tonga, margi- 

 nibus sub-acidis ac f uteris crassis vix promitientibus instructa ; valvis in medio 

 convexis atque margines versus undique declivis, concentrice regulariter ac confertim 

 striolatis, striis sulcis latioribus nonnuilis ad intervalla inter rtijytis. Cardo in valva 

 dextra duobus dentibus cardinalibus dicergentibus penitus divisis, in valva sinistra 

 tribus, dente postico tenui, fossa lata ab alteris duobus anterioribus compressis ac 

 valde prominentibus separata, instructus ; siim pallii prof undo, latiusculo, oblique 

 ascendente. 



Length of largest specimen ... ... ... ... 56'5 m. m. 



Height : length ... ... ... ... 0-90 - 0-95 



Thickness : height ... ... ... ... 0-43 - 0-49 



This is one of the finest shells occurring in the South Indian cretaceous 

 deposits. Its rounded discoidal form, with slightly prominent umboues, thickest 



